1. Field of the Invention
This invention pertains to fiber-forming melt-spinnable aromatic polyesters and to high modulus filaments thereof.
2. Description of the Prior Art
A class of aromatic polyesters that form optically anisotropic melts from which oriented filaments can be melt-spun has been described in U.S. Pat. No. 4,118,372 to Schaefgen. The polyesters which are described in the aforementioned reference are derived primarily from para-oriented dihydric phenols and para-oriented aromatic dicarboxylic acids. Filaments that are melt-spun from such polyesters can be heat treated to high tenacity and modulus.
This invention provides different anisotropic-melt-forming polyesters which can be melt-spun into filaments of high as-spun modulus [e.g., greater than 200 g/denier (177 dN/tex)]. The novel filaments can also be heat treated to increase their tenacities, preferably to a level in excess of 10 g/denier (8.84 dN/tex), while retaining moduli in excess of 200 g/denier (177 dN/tex).